Conventional dental handpieces include a rigid handle that terminates in a head that houses a pneumatically driven turbine. High-pressure operating air is coupled to the handpiece. Actuation of the handpiece causes the high-pressure air to be directed to the head for driving the turbine. A bur or drill connects to the turbine to rapidly rotate as the turbine is driven. The handpiece is also connectable to a source of water so that cooling water may be ejected from the head as the drill is used in a conventional dental procedure.
In the past, lights have been connected to dental handpieces for illuminating the work area inside the dental patient's oral cavity. One way of providing the illumination is to mount a high-brightness lamp within the coupled end of the handpiece (that is, the end of the handpiece away from the head), and to transmit the light through the handpiece via a fiber optic component that terminates near the head of the handpiece. Light emitting from the terminus of the fiber optic component illuminates the work area.
Proper illumination, and the accurate rendition of tissue colors, requires a handpiece light that provides the very bright or "white" light that is available from conventional tungsten-halogen lamps.
Tungsten-halogen lamps are relatively expensive and, like other incandescent lamps, have a limited service life. Accordingly, designs in the past have provided mechanisms that tend to conserve the service life of the lamp and make it easy to replace a used lamp. For example, the activation of the handpiece light may be coupled to actuation of the handpiece so that the light is on only when the handpiece is used. When the handpiece is stopped, the lamp will typically remain illuminated for a brief period so that the light can be used for further inspection. After that delay period, the lamp is automatically turned off.